An image compression method s used for processing a plurality of pixels of an image. The X-Y addressable sensor in this embodiment can have either the first and second bandwidths being different, or the first and second bandwidths are the same. An electrolyte membrane is disposed between a pair of electrodes and a pair of diffusion medium layers. The diagnostic-program loading unit loads a processor-diagnostic program for diagnosing a plurality of functions of the first processor into an area of the main memory other than the defective area identified by the memory-diagnostic unit. The display device has a plurality of fixed members installed parallel to each other over a substrate, the member being apart from each other; and a plurality of moveable members being driven with the fixed members by a statically electric force to switch a path of lights incident from the substrate.